import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description: 牛客网.简单题.字符个数统计
 */
public class Test {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        boolean[] ch = new boolean[128];
        int count = 0;
        for(int i = 0; i < s.length(); i++){
            if(ch[s.charAt(i)] == false){
                ch[s.charAt(i)] = true;
                count++;
            }
        }
        System.out.println(count);
    }
}
